Hitherto, oral administering formulations containing nicardipine hydrochloride have been developed but an injectable composition containing nicardipine hydrochloride has not yet been developed. This is because in the case of using the compound as an injectable composition, the compound shows a reduction in solubility according to the kind of isotonizing agent used and thus an injectable composition having a desired concentration cannot be obtained or the stability of an injectable composition if obtained is insufficient.
The inventors have investigated the possibility of obtaining a desired concentration of nicardipine hydrochloride and the stability of an injectable composition thereof by adding various additives for overcoming the above-described difficulties. As the result of the investigation, it has been found that when sodium chloride which is usually used as an isotonizing agent for injections is added, a desired concentration of nicardipine hydrochloride is not obtained and the injectable composition is insufficient in stability.
As the result of further investigations, it has been discovered that when nicardipine chloride is dissolved in water together with 2 to 7 W/V% of a polyhydric alcohol, a stable aqueous solution of nicardipine hydrochloride is unexpectedly obtained and based on the discovery, the invention has been attained.